Depends upon the year, and which 396 it is, but, 4, to 8 degrees advanced, or BTDC, should make it run best.
6 degrees advanced, or BTDC.
Right around 6 degrees advanced, with todays pump gas.
12 or 13 degrees
6 degreed advanced or BTDC.
I would set it by ear, and performance.
a Chevy 396 bear block ways, right at 200 pounds.
Yes.
about 685 pounds dry
yes
yes
180, to 200.
No it is not an interference engine.